Gravity type wheel or roller conveyors are well known in the art and are used to transport articles from one point to another without the requirement for external sources of power to move the articles. A typical gravity type wheel or roller conveyor comprises an inclined, elongated frame having a series of wheels or rollers which are arranged along the frame with the rotational axes of the wheels or rollers being located perpendicular to the longitudinal direction of the frame. Articles loaded onto the conveyor at its top or higher end are supported by a portion of the wheels or rollers. As gravity works on the articles loaded onto the conveyors, the articles move over the wheels or rollers towards the bottom or lower end of the frame. Different wheels or rollers support the articles as they continue their movement along the conveyor.
While some of these gravity type wheel or roller conveyors operate effectively without any type of external control, when the length of the wheel or roller conveyor and/or the weight of the articles being conveyed increases significantly, it becomes necessary to add external controls to the conveyor to limit the speed and acceleration of the articles as they move along the conveyor.
Various methods have been proposed to control the movement of the articles as they travel along the conveyor. Most of these methods involve the use of intermittently actuated brakes. One known gravity type wheel or roller conveyor employing an intermittently actuated brake utilizes a plurality of rubber support rollers having internal brakes associated therewith for intermittently stopping the wheels or rollers. However, successful control of the wheels or rollers can be achieved only when the operating conditions are precisely controlled. When variations in the operating conditions occur, the brakes do not always stop the wheel or rollers and thus proper control of the wheels or rollers, namely intermittent braking thereof, does not always result.
Another known wheel or roller conveyor uses an elongated brake member positioned below the wheel or rollers. This elongated brake member is moved upwardly by inflation of a flexible hose for engaging the wheels or rollers to periodically brake their rotation. While this system is at least partially effectively for controlling the rate of movement of the articles down the conveyor, the system still possesses undesirable structural and operational features. For example, the brake is applied only when the hose is inflated. Accordingly, when a failure in the inflating system or hose occurs, the brakes cannot be applied and the movement of the articles along the conveyor is uncontrolled.
Yet another known wheel or roller conveyor uses a stationary elongated brake member or brake plate positioned adjacent to the wheels or rollers. This type of wheel or roller conveyor, rather than moving the brake member up and down, moves the wheels or rollers up and down by inflation of a flexible hose. When there is no pressure within the hose, the wheels or rollers are positioned below the brake member or brake plate. Upon the pressurization of the hose the wheels or rollers are moved upwardly to contact and raise the articles off of the brake plate and onto the wheels or rollers for movement down the conveyor. When pressure is subsequently released, the articles come to rest again on the brake plate. In this type of wheel or roller conveyor, the wheel or roller system is cyclically raised and lowered so that the articles are cyclically raised off the stationary brake plates to permit a gravity urged advance along the conveyor, followed by lowering the article onto the stationary brake plate to stop the articles. This cyclic action therefore achieves a high level of speed control. For this type of wheel or roller conveyor, any failure of the inflation system or hose causes the articles to come to rest on the brake plate and does not allow continued movement of the articles down the conveyor.
Various refinements to the movable wheel or roller type of conveyor have been proffered. These include designs which incorporate alignment structures for insuring that the articles remain in the proper position on the conveyor as it moves down the conveyor and designs which specifically locate the braking plates in relation to a wooden pallet containing the articles such that the nails of the wooden pallets are continuously pounded into the pallets as the pallets make their way down the conveyor.
While the above noted wheel or roller conveyors have been utilized in industry, they all have the problem that each application which requires a wheel or roller conveyor requires a new size or design of wheel or roller conveyor in order to physically accommodate the wide variety of sizes of articles and/or pallets which need to be conveyed. This is especially true where the wheel or roller conveyor incorporates an alignment structure or when the wheel or roller conveyor is used to reset nails in pallets. The prior art alignment structures rely on contact between an angled alignment bracket on the conveyor with the articles or pallets. Therefore the width and type of the conveyor has to be designed for specific articles or pallets. Similarly when the brake plate is also used to reset nails in the pallets, the brake plates need to be positioned directly under the nails thus requiring specifically dimensioned conveyors for specific pallets. Once a pallet or article size changes, the conveyors must also be changed.
Accordingly, what is needed is a wheel or roller conveyor which is adjustable in order to accommodate a wide variety of pallet or article sizes. The present invention provides the art with an modular wheel or roller conveyor system which is created using a number of interchangeable standard components. The assembled modular conveyor is easily reworked using the interchangeable standard components to provide a wheel or roller conveyor which is capable of accommodating a wide variety of pallet and article sizes.
Other advantages and objects of the present invention will become apparent to those skilled in the art from the subsequent detailed description, appended claims and drawings.